The SeaStar CIuster Manifold system was engineered as A low cost alternative to larger and more expensive completion template designs. Utilizing field-proven equipment and installation techniques, it was the first of its kind to be installed in the Gulf of Mexico. The Cluster Manifold system allows the connection of flowlines from adjacent satellite wells and numerous in field flowlines consisting of export, service, and methanol lines. With new technological advances, and a variety of flowline connection systems on the market today, deep water completions are being used with increasing frequency. Subsea operations are becoming more routine and installation times are being reduced. The SeaStar system was successfully installed in Garden Banks Block 70/71 in the Gulf of Mexico during the first quarter of 1995. Currently two (2) 4'x2') 10,000 psi lay-away trees are installed and connected to the manifold. Production is being processed at a Marathon platform in Vermilion Block 386B approximately 13.5 miles away from the subsea installation.
The SeaStar development is located in Garden Banks Block 70/7 1 approximately 120 miles south of Cameron, Louisiana. The water depth at this location is 750 ft. The subsea equipment consists of a 4-slot manifold system, two 4'x2' 10,000 psi lay-away trees with retrievable choke inserts, electro-hydraulic (E/H) control system, E/H Umbilical, Umbilical Termination Assembly (UTA), flexible well jumpers with collet connector, hard pipe spool pieces with C&X connectors for the 6' export flowline and 2' service jumper, and four (4) 2' methanol lines. The manifold is used to commings gas production from up to four wells and deliver the production gas via dual 6' subsea pipelines to a host platform processing facility 13,5 miles distant in Vermilion Block 386B. An existing subsea sales gas pipeline system then transports the processed gas to shore.
Economic and feasibility studies were conducted from March to August of 1993 to determine the optimum development scenario. The subsea tie-back to an existing facility was chosen over a new-build, fixed platform, due to its low cost and optimum feasibility. From August to December of 1993, predevelopment engineering studies were conducted to determine overall project costs. In early January 1994, the %&tar project was kicked off.
When the project was kicked off in January 1994, three (3) wells had already been drilled, two in GB 70 and one in GB 71. The wells were drilled using a spacer template which provided a 16 R spacing between the three wells. The northern most well (GB 70 #2) was suspended following testing and will not be completed. Fig-1 shows the as-built field layout of the Manifold system, 6' and 2' hard pipe spool pieces, three well locations, two 6' flowline skids, 2' service line skid, four 2' methanol pipe lines, and the E/H umbilical.